Effects of competitive cutaneous stimuli on pain thresholds in the monkey*
Karen L. Barnes, Ph.D.
Division of Research
John P. Conomy, M.D.
Department of Neurology
In the late 1920s Bishop and Erlanger1 performed a series of experiments which suggested that pain could be diverted or occluded by competing nervous system activity. In an ingenious series of experiments performed on peripheral nerves they concluded that pain could be diminished by the peripheral occlusion of nerve impulses arising at a great distance from the brain. A more recent conceptual model of the competitive inhibition of pain stimuli suggested by Melzack and Wall2 is known as the Gate Control Theory of Pain. Although there has been extensive theoretical analysis of this system, the physiologic and behavioral evidence for its actual functioning presence in animals or man has not been forthcoming.3–5 Lack of physiologic proof, however, has not prevented the system from being employed in methods of treating pain.6, 7 An industry has sprung up over the past 10 years which claims to use the gate theory as a means of alleviating chronic, intractable pain with the use of electrical stimulators to deliver “pain-ablating” impulses to the skin or deep structures to render certain synaptic junctions unavailable for the transmission of pain impulses. When the use of the skin stimulation systems has been put to controlled clinical testing, stimulation pairing has not uniformly been found to decrease pain perception.8, 9
The present study employs behavioral experimentation to test the implications of the gate control mechanism for the behavioral response to noxious stimulation. Briefly, the gate theory states that if large fiber input predominates at synaptic gates such as the substantia . . .